I'm definitely on board with Denny and Dave here. Try bittering a given beer to about 40-45 IBUs with any noble hop, then try, say, chinook to the same 40-45 IBUs. I absolutely guarantee the difference will be very noticeable.
But is the difference in bitterness or in what is typically described as flavor? For example if I bitter with Amarillo with no late additions or dry hopping, will I get citrus/tangerine in the final product? I doubt it.
My guess is that the different bittering hops just present different bittering flavors - different alpha acid makeup - but I seriously doubt any noticeable oils remain after a 60 minute boil. For me to be convinced it would take a lab evaluation.
I would be willing to wager that some hop oils will remain. Which ones and how much are the question. There would have to be enough to remain over the taste threshold, and that is the real question.
I think the biggest difference is likely differing amounts of the various iso-AA's, but I'd be willing to put a friendly wager that some beta acids, hop oils, or some derivative thereof, may also make a contribution.